• Title, Summary, Keyword: Radical polymerization

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Titanium Complexes: A Possible Catalyst for Controlled Radical Polymerization

  • Kwark, Young-Je;Kim, Jeong-Han;Novak Bruce M.
    • Macromolecular Research
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    • v.15 no.1
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    • pp.31-38
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    • 2007
  • Pentamethylcyclopentadienyltitanium trichloride, bis(cyclopentadienyl)titanium dichloride ($Cp_2TiCl_2$), and bis(pentamethylcyclopentadienyl)titanium dichloride were used in the polymerization of styrene without the aid of Group I-III cocatalysts. The properties of the resulting polymer indicated that polymerization was more controlled than in thermal polymerization. The kinetic studies indicated that a lower level of termination is present and that the polymer chain can be extended by adding an additional monomer. To elucidate the mechanism of polymerization, a series of experiments was performed. All results supported the involvement of a radical mechanism in the polymerization using $Cp_2TiCl_2$. The possibility of atom transfer radical polymerization (ATRP) mechanism was investigated by isolating the intermediate species. We could confirm the activation step from the reaction of 1-PEC1 with $Cp_2TiCl$ by detecting the coupling product of the generated active radicals. However, the reversible deactivation reaction competes with other side reactions, and it detection was difficult with our model system.

Novel thermal radical initiators based on a triazene moiety for radical polymerization

  • Kang, Seokwoo;Kim, Taemin;Kim, Beomjin;Jeong, Yeonkyu;Park, Young Il;Noh, Seung Man;Park, Jongwook
    • Journal of Industrial and Engineering Chemistry
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    • v.68
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    • pp.1-5
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    • 2018
  • In this study, we designed and synthesized novel thermal radical initiators of BTAP (1-phenyl-3,3-dipropyltriazene), BTACP (1-(phenyldiazenyl)pyrrolidine), BTACH (1-(phenyldiazenyl)piperidine), and BTACH7 (1-(phenyldiazenyl)azepane) based on a triazene moiety to provide a thermal initiator for radical polymerization. The synthetic method is valuable due to the simplicity. In addition, the synthesized thermal initiator did not affect the color of the polymer. Among the four initiators, the polymerization time for the BTACH of the 6-membered ring decreased by 67%, as opposed to the polymerization time without initiator. Conversion after polymerization was over 92%. DSC experiments also showed that the initiator with hexagonal rings had the lowest peak polymerization temperature of $160^{\circ}C$. Our study suggests a promising new initiator system that is effective for radical polymerization.

Polymerization of Vinyl Monomers Initiated by Thianthrene Cation Radical with Potential Biological Activity

  • Lee, Beomgi;Kim, Seongsim;Park, Jaeyoung;Cheong, Hyeonsook;Noh, Ji Eun;Woo, Hee-Gweon
    • Journal of the Chosun Natural Science
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    • v.5 no.2
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    • pp.127-130
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    • 2012
  • Polymerization of vinyl monomers is promoted by thianthrene cation radical as a part of our research concerning the reactions of various agents with readily isolable, yet highly reactive species and elucidate the biological activity. Thianthrene cation radical initiated the homopolymerization and copolymerization of styrene and ethyl vinyl ether. The polymerization yields decreased as the concentration of phenylacetylene or diphenylethylene increased. Such polymereization by cationic thianthrene radical could provide some clues for the reaction in living animals. Comments on possible polymerization mechanisms were suggested.

The Kinetics of Radical Polymerization of Styrene with Tricaprylymethylammonium Chloride as a Phase-Transfer Catalyst (상이동촉매인 트리카프릴메틸암모니움 클로라이드를 사용한 스티렌 라디칼중합의 동력학적 연구)

  • Park, Sang-Wook;Sohn, In-Joe;Park, Sang-Bo
    • Journal of Adhesion and Interface
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    • v.2 no.2
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    • pp.11-19
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    • 2001
  • The phase-transfer catalyzed radical polymerization of styrene was carried out using tricaprylylmethylammonium chloride as a phase-transfer catalyst in a two-phase system of an aqueous $Na_2S_2O_8$ solution and toluene at $60^{\circ}C$ under nitrogen atmosphere. The initial rate of radical polymerization was expressed as the combined terms of concentrations of quaternary onium cation and peroxydisulfate anion in the aqueous phase rather than the fed concentrations of catalyst and $Na_2S_2O_8$. The observed initial rate of radical polymerization was used to analyze the radical polymerization mechanism with a cycle phase-transfer initiation step in the heterogeneous liquid-liquid system. The viscosity average molecular weight of polystyrene was inversely proportional to concentration of $Na_2S_2O_8$ expressed as $[Q^+]([S_2O{_8}^{2-}]{\alpha}_2)^{1/2}$ derived by the radical polymerization mechanism.

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New Tridentate Ligands with Mixed Donor Atoms for Cu-Based Atom Transfer Radical Polymerization

  • Cho, Hong-Youl;Han, Byung-Hui;Kim, Il;Paik, Hyun-Jong
    • Macromolecular Research
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    • v.14 no.5
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    • pp.539-544
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    • 2006
  • 2-Furancarboxaldehyde-2-pyridinylhydrazone (FPH) and 5-methyl-2-furancarboxaldehyde-2-pyridinylhydrazone (MFPH) were synthesized and used as tridentate ligands of copper (I) bromide for the atom transfer radical polymerization of methyl methacrylate (MMA) and styrene. The polymerization of methyl methacrylate achieved high conversion and yielded polymers with a good control of molecular weight and low polydispersity (PDI=1.33). Higher PDI were observed in the polymerization of styrene. Using 1-phenyl ethylbromide (PEBr) and ethyl 2-bromoisobutyrate (EBiB) as model compounds for the polymeric chain ends, the activation rate constants of the new catalytic systems were measured. These results were correlated with the polymerization results and compared with another catalytic system previously reported.

Estimation of Activation Energy for the Free Radical Polymerization by Using Isoconversional Analysis (등전환 분석(Isoconversional Analysis)를 이용한 자유라디칼 중합의 활성화 에너지 계산)

  • Chung, I.
    • Elastomers and Composites
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    • v.39 no.4
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    • pp.281-285
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    • 2004
  • In this paper, the simple way to evaluate the value of the activation energy for the overall rate of free radical polymerization by using DSC thermograms was studied using free radical polymerization or butylacrylate as a model. Activation ehergies were determined at heating rates of 1, 2, 5, and $10^{\circ}C/min$ by applying the multiple scanning-rate methods of Kissinger, Osawa, and half-width methods as well as the single rate method of Barrett. The value of the overall activation energy measured was closely matched with the values calculated from individual data. This work also demonstrated that the use of the isoconversional method was a simple and effective way to estimate the activation energy for the overall free radical polymerization.

Iron Catalyzed Atom Transfer Radical Polymerization of Methyl Methacrylate Using Diphenyl-2-pyridylphosphine as a Ligand

  • Xue, Zhigang;Noh, Seok-Kyun;Lyoo, Won-Seok
    • Macromolecular Research
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    • v.15 no.4
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    • pp.302-307
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    • 2007
  • The living radical polymerization of methyl methacrylate (MMA) by atom transfer radical polymerization, (ATRP) employing a $Fe(II)X_2/diphenyl-2-pyridyl$ phosphine (PyP) catalytic system (X=Cl, Br), was investigated using several initiators and solvents at various temperatures. Most of the polymerizations with the PyP ligand were well controlled, with a linear increase in the number average molecular weights ($M_n$) vs. conversion, with relatively low molecular weight distributions ($M_w/M_n=1.2-1.4$) throughout the reactions. The measured weights matched those of the predicted values. The ethyl-2-bromoisobutyrate (EBriB) initiated ATRP of MMA, with the $Fe(II)X_2/diphenyl-2-pyridyl$ phosphine catalytic system (X=Cl, Br), was better controlled in p-xylene at $80^{\circ}C$ than the other solvents used in this study.

Investigation on Chain Transfer Reaction of Benzene Sulfonyl Chloride in Styrene Radical Polymerization

  • Li, Cuiping;Fu, Zhifeng;Shi, Yan
    • Macromolecular Research
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    • v.17 no.8
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    • pp.557-562
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    • 2009
  • The free radical polymerization of styrene was initiated with azobis(isobutyronitrile) in the presence of benzene sulfonyl chloride. Analysis of the terminal structures of the obtained polystyrene with $^1H$ NMR spectroscopy revealed the presence of a phenyl sulfonyl group at the ${\alpha}$-end and a chlorine atom at the ${\omega}$-end of each polystyrene chain. The terminal chlorine atom in the polystyrene chains was further confirmed through atom transfer radical polymerization (ATRP) of styrene and methyl acrylate using the obtained polystyrenes as macroinitiators and CuCl/2,2'-bipyridine as the catalyst system. GPC traces of the products obtained in ATRP at different reaction times were clearly shifted to higher molecular weight direction, indicating that nearly all the macroinitiator chains initiated ATRP of the second monomers. In addition, the number-average molecular weights of the polystyrenes increased directly proportional to the monomer conversions, and agreed well with the theoretical ones.

Synthesis of block copolymer of polystyrene and polyethylene glycol methyl ether methacrylate(PEGMA) by ATRP (atom transfer radical polymerization) (ATRP(atom transfer radical polymerization)에 의한 polystyrene과 poly ethylene glycol methyl ether methacrylate(PEGMA)의 블록 공중합체의 합성)

  • Kim, Sang-Hern
    • Journal of the Korean Applied Science and Technology
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    • v.26 no.3
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    • pp.306-316
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    • 2009
  • In this study, block copolymer of polystyrene and polyethylene glycol methyl ether methacrylate(PEGMA) by ATRP(atom transfer radical polymerization) method was synthesized. 4 arm-molecule which contained halogen atom was synthesized for an initiator. With 4 arm-molecule monodispered polystyrene were synthesized by ATRP method. The molecular change of synthesized monodispersed polystyrene with respect to time was investigated and living polymer characteristic was confirmed. Block copolymer of polystyrene and polyethylene glycol methyl ether methacrylate(PEGMA) was synthesized by ATRP with macroinitiator which was synthesized from the monodispersed polystyrene(Mn=12000). The molecular weight of obtained PS-b-PEGMA was 22,000.